That VS1053-based MikroElektronika board has not been tested. But this similar one from Adafruit has been reported to work. Scroll down to the part of the thread where the code was fixed.
http://forum.pjrc.com/threads/23970-Teensy-3-0-Ada-FRuit-VS1053-Audio-Breakout-Board-Problems
If you're going to use a VS1053, and you want it to be a trouble-free experience, Adafruit's board is probably your best path. There are also lots of very cheap VS1053 boards from no-name Asian merchants (eg, on Ebay). I have one in my big box of waiting-to-be-tested hardware. Those can probably work too with Adafruit's code, but you may have to do some fiddling, which might turn out to be easy or it could end up being very difficult.
But since you're talking about FLAC, I'm going to guess this is an "audiophile" project. So first, let's consider the output hardware.
There are roughly 5 categories of audio output hardware. In order from lowest to highest quality.
- PWM or other pulse averaging.
- DAC integrated into a mixed-mode chip. The VS1053 is an example.
- Low-power dedicated chip DAC or Codec. The upcoming audio board will be in this category.
- High performance DAC with low cost parts.
- High performance DAC with top quality output filter & crystal clock. I'm considering publishing a DIY design...
If we talk about these in terms of noise+distortion in terms of
effective number of bits, you generally get up to about 13-15 bits at #3. That's simply the level of performance possible with today's technology when optimizing for low power consumption. Every chip claims to use 24 bits, and internally they do manipulate that many bits. But not even the very best DACs can achieve 146 dB signal to noise+distortion.
The
VS1053 doesn't spec S/N+D in dB. They do specify THD at 0.07% (page 8 of the datasheet), which is really pretty terrible, only -31.5 dB. So even though the chip claims to support 24 bit FLAC decoding using a software plugin, and the built-in DAC is supposed to have 18 bits, in terms of effective number of bits (signal to noise+distortion), the analog circuitry in the chip adds a huge amount of distortion. That's actually pretty typical for low-cost mixed-mode chips. They're rarely anywhere near as good as a dedicated DAC or Codec chip.
The good news, if you only want to build a portable player that sounds ok, is human hearing is pretty insensitive to most types of distortion, especially harmonic distortion.
The bad news, if this is an audiophile application, as I suspect it is since you're interested in FLAC, is to truly get the S to N+D ratio over 96 dB requires expensive and power hungry hardware.
I can tell you the first release of the upcoming audio library will support 16 bit WAV files, but not FLAC.